Low air pressure alarm for motor vehicle tires



Nov. 13,1951 Q DY' 2,574,863

LOW AIR PRESSURE ALARM FOR MOTOR VEHICLE TIRES Filed Sept. 5 1945 Patented Nov. 13, 1951 Low Am PRESSURE Anknlvfron' w c mits titres ca e. ah ia.

whee rim an .r is eht rl paeea .cfrqmit e, user. ikivhile ueh posit on rmakeslnolnoi ei l i eke a m, is so lpivo all mounted n th metalwheel dislgthatr when the air pressure in .theetiregoes down a ce''rtairr,degree the bulgingr ofi the r w l lll fih .9 hrew-the shocker-, utwardly. YSQ the whe l tates hddthe lsno lser arm) leaves llabu ga. h .v sn ck m-uWi11:W n&-back and a strikefthewheel rim thus serving to make a noiseh and notify the driver gii the condition, of; the tire Wit h i the ah, e, and othergohjectslin, view,; my, d," t nl g will h NQ ISt UQUiOIL arran er me i fe id-Q9. ati0. oi thevariqus parts qm yr. dev er mi a bie lq nt mnl dl te ea. t ,d; a veir ina er m re.. u11yl se hr po nted out in my claims. .andill strated in the aeeomta m umw n s wh n f o rF ifeQl, howee ide e e e ioe i e -i u m bile wheel and tire equipped with a, low airrpresw u e ala m smhod ine intenti n-.the hub cap eing omitted in grder that the other parts -belmb c erlase m Figure 2 visa det i1 sectional viwtskfibnlhe" line 22 of Figure 1. ,z +1- Figure 3 is a gletail sectional view taken on the line 3-4 of Figure 1.

Figure 4 is a plaiijtiieiw.'bfltheikriocler arm. F r 5. .5 .greet ven res el n; L t W ofmy'low pressure alarmshown l -and; shows more clearly some of the structural details thereof. v Figure 61s an enlargementloffa portion ofl Fig-fi .1 ures' z and 3, andisl a cross=s'e'ctional detail view showingjthe cooperationbetwieenflth pivot we'd'ge' andithe crotchiof.theknockeharinizii Figure 7 is; amgreatly enlarged'view tak'n'onu In the drawings, the. referencenumeral II] indicates the metal disktype vehicle wheel havingth" ordinary detal'iable'rim I2, on which is the 'usiialt'ire [4.

My low pressure alarm includes a knocker arm indicated generally at I6. I will now describe the way in which this knocker arm is assembled on the wheel disk III. In the body or disk of the wheel I cut a radially elongated slot l8. On the 50 opposite sides of the slot l8 are oblong slots 20. On the inside of the wheel at the sides of the slot I8 and radially outwardly with relation to the slots 20 are fixed, spaced pairs of ears 22 connected by a pin 24 on which is mounted the eye 55 26 of an eye bolt 28.

The-shape oi"- the knocker arm"! 6 is illustrated imthe drawing; lt has a cehtral waist-portion 39-which* may-'=have =a radially extending slot 32 provided :simplyto remove the weight" of-"tlie" metal. At its outer'end the knock'er arm has the heavy p1ate-like-portion 34 slightly offset out: vz ardly- -as indicated at: lheinner end of the knocker arm has the laterally 'xtending portion 38* in w-hichare formed the radially inwardly extending: lugs: 39 wliich" proj ect into" the slots 20? Betweenthedugs-GS, the knoclr a'r'in lanes air outwardly extending flange flfl into Xv'hieh' the" slot 3l-extends to receive the eye bolt 28 as shown in Figure 2. I?

e-Elhe edge of'a=-pivot 'wedg 42 'ngags th bottomot: the- V formedby the body of-'-the ki'lo'cker; a1=m-l6 and; its flange "40.-

The wedge fl ha' s 'a; l central-=outwardly proj eating tubular' extension flethl'ough which the eye bolt-projects. (Dnth'e eye-bolt and on the tubular extension fl is a- 'coil spring 46 held -in place by spr-ing cap 48 and a" nut-50 onthe eye boltk The tension of' thesp'ririg I can -be adjusted bythe-adjustment of=then'iit 56;

On opposite sidesof the outer end of the slot 32 are bolts 52 which 'are'ieiitend'ed throughthe" kIlOCkGIL" arm, with their heads fiin" bdsition to strike the-rim +2 in: the operation" of'thfe ln'riockei" arms Thin washers 54 are placedon the bolts 52* between their heads and tli knocker am 46* as shown, for instanceyin" Figure- 3. GII SppQ'site sides of the hnoeker arm are washers 56 and adjustable nutS58-w I hje number-and thickness of the- =washers 54 will-determi-ne the tire---'pressure "at-whichth'e' alarm device will function*by-determining the distanceiromthe tire at which the plate portion 34is-nornaally se; In actual oprationj when the car'istraveling at a certain speed, say 29 miles or moreper'hou'r, hQJZIE hEPf ,l' h knqck r arm, efiected by can l ugal 9rcelahdhthe tension ofthel. spr

le sneaker arm; withatheiheads or b0 i a ainst the :rim andno'noise is madew'.

.. If when tine,all:wp tr sultew in thestire goes aW Qs qi'i flm lei from 3 .;tQi-25poundsdt is ob vious that the tire will bulge as indicated at 66 in Figure 3, at its lower part next to the ground. This will throw the knocker arm out against the tension of the spring 46 to the position illustrated in Figure 3 where the bolts 52 are spaced from the tire rim.

As the tire rotates in the direction indicated by the arrow 68 in Figure 1, and the knocker arm moves from its position at the bottom of the tire illustrated in Figure 1 to position A, the knocker arm will swing toward the tire and the rim. There will be no bulge in the tire at position A. The weight of the knocker arm plus the effect of centrifugal force, due to the forward movement of the car, plus wind pressure and spring tension, will cause the knocker arm to move sharply and strike the bolts 52 against the rim. This of course is repeated with great speed and the knocking noise 'aflords an alarm to warn the driver that the air pressure in his tire is low.

When the knocker arm is thrown outward by the bulge in the tire, the force of the spring, the force of gravity and centrifugal force, which all normally tend to hold the knocker against'the rim, are momentarily overcome, but as soon as the knocker arm leaves the bulge, these forces,

to-wit, spring pressure, wind pressure and. the

momentum of the car causin centrifugal force to be effected, permit and cause the heavy plate portion 34 of the knocker arm to swing toward the tire and cause the bolts to strike the rim.

It should be noted that when the knocker arm is extending downwardly, the wind strikes its narrow edge, but when the knocker arm is at position A, the wind engaging the plate 34 is effective in cooperating with centrifugal force and spring tension to cause the loud knocking which affords a signal.

In my use of the knocker arm, I found that the sound is intensified by the knockers tight and narrow connection with the metal of the wheel disk and the wheel cap, and that the wheel cap and wheel function as sounding boards to increase the intensity of the noise.

It will be noted that once the knocker arm is properly assembled and adjusted, no further adjustment is necessary during the life of the tire.

There are no parts which need to be oiled or greased. The knocker arm is noiseless except when affected by the bulge at the bottom of the tire when the tire pressure goes down.

I have thus provided a very simple, inexpensive and effective means for furnishing to the driver of a motor vehicle an alarm which will warn him when the tire pressure goes down.

Attention is directed to my copending application, Serial No. 516,417, now matured into Patent No. 2,400,107 issued May 14, 1946, entitled Low Air Pressure Alarm for Pneumatic Vehicle Tires which patent is directed to another form of low pressure alarm for motor vehicle tires.

While I have shown a particular embodiment of my invention, it will be understood of course that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the claims appended hereto to cover any such modifications or substitutions of equivalents as fall within the true spirit and scope of my invention.

I claim as my invention:

1. A low pressure alarm device for attachment to a vehicle wheel including a central disc having an outer flange and an inflated tire seated in said flange, said device comprising an arm, means for swingably connecting one end of said arm to said disc between the disc center and said flange, said arm extending past said flange and having its other end engageable with the side of said tire, said arm being shaped between its ends to permit constant contact with said flange only when said tire is fully inflated, a transverse flange on said arm at the point where said arm is swingably connected to said disc defining with said arm a V-shaped seat, a V-shaped wedge fitting said seat and lifted therefrom when said arm is swung away from said flange, resilient means biasing said wedge into said seat, and means for supporting said resilient means from said disc, whereby rotation of said wheel with said tire incompletely inflated and therefore laterally bulged at its bottom will effect intermittent knocking impact of said arm with said flange.

2. A device according to claim 1 for attachment to a vehicle wheel including a disc formed with two spaced apertures between the disc center and the disc flange, said device comprising means for swingably connecting the arm engageable with the tire side to said disc including spaced axial lugs on the connected arm end each projecting through one of said disc apertures and two aligned lateral projections from said arm abutting said disc outside said apertures defining a pivot for swinging said arm with respect to said wheel disc, said projections being aligned with the transverse flange on said arm.

3. A device according to claim 1 for attachment to a vehicle wheel including a disc formed with an aperture between the disc center and the disc flange, said device comprising an arm apertured at its V-shaped seat, an axially apertured wedge, resilient wedge biasing means and means for supporting said resilient means including a rod loosely threaded through said wedge aperture and projecting from both ends thereof,'one end of said rod passing through said arm and disc apertures, means for swingably supporting said rod end from said disc, a collar on the other end of said rod, and a spring around said rod between said collar and said wedge.

4. A device according to claim 1 comprising an arm having a transverse projection of adjustable length opposed to the tire flange for knocking impact therewith when the tire is incompletely inflated.

CHARLES LIBBE DYKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,025,100 Schneider Apr. 30, 1912 1,729,619 Laro Oct. 1, 1929 1,763,639 Christophersen June 1'7, 1930 2,368,617 Rykken Feb. 6, 1945 2,400,107 Dyke May 14, 1946 FOREIGN PATENTS Number Country Date 266,895 Germany Jan. 4, 1913 

